TY - JOUR

T1 - High resolution analysis of opening and sliding in fatigue crack growth

AU - Sangid, Michael D.

AU - Pataky, Garrett J.

AU - Sehitoglu, Huseyin

AU - Hamilton, Reginald F.

AU - Maier, Hans J.

N1 - Funding information: The research was supported by a Critical Research Initiative (CRI) at the University of Illinois and partly by the US Department of Energy Nuclear Energy University Program (NEUP) under grant DOE-INL-00091210 and a CRDF Award under grant RUE1-2983-TO-10. The authors would like to thank Prof. Yuri Chumlyakov of Siberian Physical-Technical Institute, Russia for providing the single crystal specimens.

PY - 2011/11/11

Y1 - 2011/11/11

N2 - The use of digital image correlation analysis during fatigue crack growth (FCG) of polycrystalline and [1 1 1] oriented single crystal specimens of 316L stainless steel allows for the investigation of mixed mode crack propagation in the vicinity of the crack tip. This technique offers significant benefit in addressing crack closure at the microscale compared to the large body of work studying this phenomenon at the macroscale. Understanding of FCG behavior relies on the sliding (mode II) details which can be rather complicated. In this study, the mode I (opening) and mode II (sliding) mechanisms are differentiated within the single crystal specimens for slanted cracks. Further, crack opening displacement profiles are obtained in mode I and mode II, which are used to quantify crack closure in each specimen. Finally, the irreversible strain within the plastic zone ahead of the crack tip is measured during crack propagation. The results show that [1 1 1] oriented single crystal specimen fatigued at R = -1 display the most slip irreversibilities due to reverse dislocation motion leading to dislocation kinks/jogs. As a result, residual stress is diminished at the crack tip thereby resulting in earlier crack opening within the loading cycle.

AB - The use of digital image correlation analysis during fatigue crack growth (FCG) of polycrystalline and [1 1 1] oriented single crystal specimens of 316L stainless steel allows for the investigation of mixed mode crack propagation in the vicinity of the crack tip. This technique offers significant benefit in addressing crack closure at the microscale compared to the large body of work studying this phenomenon at the macroscale. Understanding of FCG behavior relies on the sliding (mode II) details which can be rather complicated. In this study, the mode I (opening) and mode II (sliding) mechanisms are differentiated within the single crystal specimens for slanted cracks. Further, crack opening displacement profiles are obtained in mode I and mode II, which are used to quantify crack closure in each specimen. Finally, the irreversible strain within the plastic zone ahead of the crack tip is measured during crack propagation. The results show that [1 1 1] oriented single crystal specimen fatigued at R = -1 display the most slip irreversibilities due to reverse dislocation motion leading to dislocation kinks/jogs. As a result, residual stress is diminished at the crack tip thereby resulting in earlier crack opening within the loading cycle.

KW - Crack closure

KW - Crack opening

KW - Fatigue crack growth

KW - Mixed mode

KW - Stainless steel

UR - http://www.scopus.com/inward/record.url?scp=84655164273&partnerID=8YFLogxK

U2 - 10.1016/j.ijfatigue.2011.11.001

DO - 10.1016/j.ijfatigue.2011.11.001

M3 - Article

AN - SCOPUS:84655164273

VL - 37

SP - 134

EP - 145

JO - International journal of fatigue

JF - International journal of fatigue

SN - 0142-1123

ER -